1. Field of the Invention
The present invention relates a planar motor, and more particularly to a planar motor having a stator and a mover in which permanent magnets are arranged to reduce a leakage magnetic flux, thereby increasing a magnetic flux density and generating a strong thrust.
2. Description of the Background Art
A planar motor is constructed such that a mover is moved on a plane while separated a predetermined height above or distance apart from a surface of a stator. The planar motion of the mover may be adopted to drive a head unit for mounting components on a printed circuit board in the X-Y direction in a component mounting device. In this case, in order to generate a driving force to move the head unit in the X-Y direction, the planar motor needs to have a strong thrust.
FIG. 1 is a perspective view of a planar motor in accordance with a conventional art, and FIGS. 2A and 2B are plan views of a permanent magnet part arranged on a plane surface of the stator of FIG. 1.
As shown in FIG. 1, the planar motor includes a stator 10 and a mover 20. The stator 10 includes a permanent magnet part 12 having a plurality of S-pole permanent magnets 12a and a plurality of N-pole permanent magnets 12b arranged in a grid form on the plane surface of the stator frame 11. The mover 20 includes an armature coil part 21 at the bottom surface of an armature frame 22.
In order for the armature coil part 21 to receive an electric signal, there is provided a cable 22a at one side of the mover 20. When the electric signal is applied to the cable 22a, a thrust is generated between the armature coil part 21 of the mover 20 and the permanent magnet part 12 of the stator 10.
In order to move the mover 20 in the X-Y direction on the plane of the stator by virtue of the thrust generated between the permanent magnet part 12 and the armature coil part 21, the mover 20 needs to be lifted up a predetermined height from the plane surface of the stator 10.
In order to lift up the mover 20 from the plane surface of the stator at a predetermined height, a nozzle (not shown) is installed at the mover 20.
When air is jetted through the nozzle, the mover 20 is lifted up a predetermined height from the surface of the stator 10 by virtue of the air-jetting force, and in this state, the mover 20 moves freely on the plane of the stator 10.
In order to move the mover 20 in the X-Y direction on the plane of the stator 10, as shown in FIG. 2A, the permanent magnet part 12 corresponding to the armature coil part 21 installed at the mover 20 includes a plurality of S-pole permanent magnets 12a and a plurality of N-pole permanent magnets 12b formed in a grid form on the plane of the stator frame 11.
In detail, the permanent magnet part 12 is formed in a manner that, centering around the S-pole permanent magnet 12a, a respective corner of each of a plurality of the N-pole permanent magnets 12b contacts respectively each corner of the S-pole permanent magnet 12a, or conversely, centering around the N-pole permanent magnet 12b, a respective corner of each of a plurality of the S-pole permanent magnets 12a contacts respectively each corner of the N-pole permanent magnet 12b, whereby a grid is formed.
The permanent magnet part 12, having the plurality of S-pole permanent magnets 12a and the plurality of N-pole permanent magnets 12b arranged such that each corner of each permanent magnet contacts a corner of another permanent magnet, includes quadrangular space 12c formed between the S-pole permanent magnets 12a and the N-pole permanent magnets 12b, as shown in FIG. 2A. Because of this space 12c, the packing density of the permanent magnets is low on the whole permanent magnet part 12, causing a problem that the thrust of the planar motor becomes weak.
Thus, in order to improve the low packing density of the permanent magnet part 12, as shown in FIG. 2A, the S-pole permanent magnets 12a and the N-pole permanent magnets 12b of the permanent magnet part 12 are arranged to be inclined at a predetermined angle such that each of a plurality of the N-pole permanent magnets 12b contacts a side of the four sides of a plurality of the S-pole permanent magnets 12a or each of a plurality of the S-pole permanent magnets 12a contacts a side of the four sides of a plurality of the N-pole permanent magnets 12b, as shown in FIG. 2B.
As the S-pole permanent magnets 12a and the N-pole permanent magnets 12b are arranged to contact with each other as shown in FIG. 2B, the packing density of the permanent magnet part of FIG. 2B is enhanced compared to the permanent magnet part of FIG. 2A.
In this case, however, since the S-pole permanent magnets 12a and the N-pole permanent magnets 12b are so closely arranged and polarized, the number of magnetic flux interlinkage lines interlinked with current flowing along the armature coil part 21 is reduced, so that leakage current is generated.
In addition, since the length of magnetization formed by the S-pole permanent magnets 12a and the N-pole permanent magnets 12b is shortened, the strength of the permanent magnets is reduced, resulting in that the overall thrust of the planar motor is weakened.
Therefore, an object of the present invention is to provide a planar motor which is capable of reduce a leakage magnetic flux by increasing packing density of S-pole permanent magnets and N-pole permanent magnets arranged on a plane of a stator frame as well as increasing the number of magnetic flux interlinkage lines interlinked with current flowing along an armature coil part installed at a mover frame and capable of increasing the intensity of magnet by increasing the length of magnetization.
Another object of the present invention is to provide a planar motor which is capable of reducing a leakage magnetic flux by increasing the number of magnetic flux interlinkage lines and capable of generating stronger thrust by increasing the length of magnetization and the intensity of magnet.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a planar motor including: a mover having an armature coil part installed at the bottom of an armature frame for receiving an electric signal, and a stator with a first permanent magnet part installed having S-pole permanent magnets and N-pole permanent magnets arranged in a manner that one corner of each of the N-pole permanent magnets contacts one of each of the four corners of a respective one of the S-pole permanent magnets on the plane surface of a stator frame installed facing the armature coil part of the mover, and inserted permanent magnets arranged at spaces formed as the corners of the S-pole permanent magnets contact the corners of N-pole permanent magnets.